Generally, amorphous poly(alumino-silicates) are prepared by mixing aqueous solutions of sodium silicate and sodium aluminate, allowing the resultant mixture to gel, removing water, for example, by freezing to about -5.degree. C. without precipitating solutes contained therein, and then washing out water-soluble compounds, which include substantial amounts of sodium hydroxide, sodium aluminate and sodium silicate. Such soluble residues represent an economic penalty in that the yield of desired product is low and waste disposal costs are high. Moreover, alumino-silicates with Si/Al ratios greater than 4, particularly 10 to 100, are difficult to prepare by this method and, in fact, the art suggests that the Si/Al ratio in the poly(alumino-silicate) product is not dependent on the Si/Al ratio in the reactants.
Also disclosed in the art is the preparation of poly(alumino-silicates) by acidifying a sodium silicate solution until a silica gel is formed, then combining the gel with either an alumina gel or with a sodium aluminate solution. Such poly(alumino-silicates) generally are heterogeneous.